US4329434A - Novel fluorinated cation exchange membrane and process for producing the same - Google Patents

Novel fluorinated cation exchange membrane and process for producing the same Download PDF

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US4329434A
US4329434A US06/152,847 US15284780A US4329434A US 4329434 A US4329434 A US 4329434A US 15284780 A US15284780 A US 15284780A US 4329434 A US4329434 A US 4329434A
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membrane
fluorinated
cation exchange
exchange membrane
carboxylic acid
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Kyoji Kimoto
Hirotsugu Miyauchi
Jukichi Ohmura
Mikio Ebisawa
Toshioki Hane
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Asahi Kasei Corp
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Asahi Kasei Kogyo KK
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Priority claimed from JP54085852A external-priority patent/JPS5910658B2/ja
Priority claimed from JP9030279A external-priority patent/JPS5616460A/ja
Priority claimed from JP9030179A external-priority patent/JPS5912116B2/ja
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D327/00—Heterocyclic compounds containing rings having oxygen and sulfur atoms as the only ring hetero atoms
    • C07D327/02—Heterocyclic compounds containing rings having oxygen and sulfur atoms as the only ring hetero atoms one oxygen atom and one sulfur atom
    • C07D327/04—Five-membered rings
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C309/00—Sulfonic acids; Halides, esters, or anhydrides thereof
    • C07C309/78—Halides of sulfonic acids
    • C07C309/79—Halides of sulfonic acids having halosulfonyl groups bound to acyclic carbon atoms
    • C07C309/82—Halides of sulfonic acids having halosulfonyl groups bound to acyclic carbon atoms of a carbon skeleton substituted by singly-bound oxygen atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C309/00—Sulfonic acids; Halides, esters, or anhydrides thereof
    • C07C309/78—Halides of sulfonic acids
    • C07C309/79—Halides of sulfonic acids having halosulfonyl groups bound to acyclic carbon atoms
    • C07C309/84—Halides of sulfonic acids having halosulfonyl groups bound to acyclic carbon atoms of a carbon skeleton substituted by carboxyl groups
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    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C317/00—Sulfones; Sulfoxides
    • C07C317/16—Sulfones; Sulfoxides having sulfone or sulfoxide groups and singly-bound oxygen atoms bound to the same carbon skeleton
    • C07C317/18—Sulfones; Sulfoxides having sulfone or sulfoxide groups and singly-bound oxygen atoms bound to the same carbon skeleton with sulfone or sulfoxide groups bound to acyclic carbon atoms of the carbon skeleton
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C323/00—Thiols, sulfides, hydropolysulfides or polysulfides substituted by halogen, oxygen or nitrogen atoms, or by sulfur atoms not being part of thio groups
    • C07C323/10—Thiols, sulfides, hydropolysulfides or polysulfides substituted by halogen, oxygen or nitrogen atoms, or by sulfur atoms not being part of thio groups containing thio groups and singly-bound oxygen atoms bound to the same carbon skeleton
    • C07C323/11—Thiols, sulfides, hydropolysulfides or polysulfides substituted by halogen, oxygen or nitrogen atoms, or by sulfur atoms not being part of thio groups containing thio groups and singly-bound oxygen atoms bound to the same carbon skeleton having the sulfur atoms of the thio groups bound to acyclic carbon atoms of the carbon skeleton
    • C07C323/12—Thiols, sulfides, hydropolysulfides or polysulfides substituted by halogen, oxygen or nitrogen atoms, or by sulfur atoms not being part of thio groups containing thio groups and singly-bound oxygen atoms bound to the same carbon skeleton having the sulfur atoms of the thio groups bound to acyclic carbon atoms of the carbon skeleton the carbon skeleton being acyclic and saturated
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F214/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
    • C08F214/18—Monomers containing fluorine
    • C08F214/184—Monomers containing fluorine with fluorinated vinyl ethers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F214/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
    • C08F214/18—Monomers containing fluorine
    • C08F214/26—Tetrafluoroethene
    • C08F214/262—Tetrafluoroethene with fluorinated vinyl ethers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F216/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical
    • C08F216/12—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical by an ether radical
    • C08F216/14—Monomers containing only one unsaturated aliphatic radical
    • C08F216/1466—Monomers containing sulfur
    • C08F216/1475—Monomers containing sulfur and oxygen
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F8/00—Chemical modification by after-treatment
    • C08F8/04—Reduction, e.g. hydrogenation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F8/00—Chemical modification by after-treatment
    • C08F8/12—Hydrolysis
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/20—Manufacture of shaped structures of ion-exchange resins
    • C08J5/22—Films, membranes or diaphragms
    • C08J5/2206—Films, membranes or diaphragms based on organic and/or inorganic macromolecular compounds
    • C08J5/2218—Synthetic macromolecular compounds
    • C08J5/2231—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions involving unsaturated carbon-to-carbon bonds
    • C08J5/2237—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions involving unsaturated carbon-to-carbon bonds containing fluorine
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
    • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
    • C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms

Definitions

  • This invention relates to a novel fluorinated cation exchange membrane having both carboxylic acid groups and sulfonic groups, intermediates and starting materials for production thereof and also to processes for producing such materials.
  • This invention also concerns a novel fluorinated cation exchange membrane having sulfonic acid groups with a high ion-exchange capacity and being provided with physically high strength.
  • the cation exchange membrane according to the present invention can be used in electrolysis of an aqueous alkali metal halide solution under more severe conditions than those conventionally used while maintaining excellent performance stably for a long time.
  • the ion-exchange membrane process has recently attracted great attention, because it is more advantageous in various aspects such as prevention of environmental pollution and economical saving of energy than the mercury process and the diaphragm process of the prior art and also because it can produce caustic soda having substantially the same quality as that produced by the mercury process.
  • the membrane is required to have a sufficiently high ion-exchange capacity and low water content, thus giving a high concentration of fixed ions in the membrane.
  • a higher water content is rather more advantageous. Since the water content will vary depending on the types of ion-exchange groups, the ion-exchange capacity and the concentration of external liquids, it is necessary to select the optimum combination of these factors.
  • a cation exchange membrane comprising a fluorinated polymer can be sufficiently resistant generally under the aforesaid atmosphere, but some membranes may be insufficient in chemical stability depending on the ion-exchange groups contained therein. Accordingly, it is important to select suitable ion-exchange groups.
  • fluorinated cation exchange membranes for use in electrolysis of an aqueous alkali metal halide solution.
  • a fluorinated cation exchange membrane having pendant sulfonic acid groups prepared by hydrolysis of a copolymer comprising tetrafluoroethylene and perfluoro-3,6-dioxa-4-methyl-7-octene sulfonylfluoride.
  • Such a well-known fluorinated cation exchange membrane containing only sulfonic acid groups is liable to permit permeation of hydroxyl ions migrated and diffused from the cathode compartment therethrough due to the high water content afforded by the sulfonic acid groups. For this reason, such a membrane is disadvantageously low in current efficiency.
  • electrolysis is conducted, for example, by recovering a highly concentrated caustic soda solution of 20% or higher, the current efficiency is extremely low to a great economical disadvantage as compared with electrolysis by the mercury process or the diaphragm process of the prior art.
  • the ion-exchange capacity of sulfonic acid groups may be lowered to, for example, 0.7 milliequivalent or lower per one gram of the H-form dry resin, whereby the water content in the membrane can be decreased to make the fixed ion concentration in the membrane higher than the membrane with higher ion-exchange capacity.
  • the current efficiency at the time of electrolysis can slightly be prevented from being lowered.
  • the current efficiency can be improved to about 80%.
  • improvement of current efficiency by reduction in ion-exchange capacity of the membrane will cause a noticeable increase in the electric resistance of the membrane, whereby no economical electrolysis is possible.
  • the membrane having carboxylic acid groups is higher in electric resistance than the membrane having sulfonic acid groups.
  • the power unit may be undesirably very high.
  • the membrane is prone to shrink when used for a long time in a highly concentrated alkali under severe conditions until it is hardened so as to be brittle, resulting in layer peel-off or crack formation, whereby current efficiency may disadvantageously be lowered.
  • a cation exchange membrane prepared by bonding films of a fluorinated polymer having carboxylic acid groups or groups convertible to carboxylic acid groups (hereinafter referred to as precursors) and a fluorinated polymer having sulfonic acid groups or precursors thereof or by molding a blend of said polymers into a film, followed by hydrolysis, as disclosed by Japanese published unexamined patent applications No. 36589/1977 and No. 132089/1978 and U.S. Pat. No. 4,176,215.
  • precursors a fluorinated polymer having carboxylic acid groups or groups convertible to carboxylic acid groups
  • the blended product is also entirely insufficient from the standpoint of complete utilization of higher current efficiency of carboxylic acid groups and lower electric resistance of sulfonic acid groups. It merely exhibits the intermediate characteristic of both properties.
  • Japanese published unexamined patent applications and another Japanese published unexamined patent application No. 23192/1977 also disclose a cation exchange membrane prepared by ternary copolymerization of a vinyl monomer having carboxylic acid groups or precursors thereof, a vinyl monomer having sulfonic acid groups or precursors thereof and a fluorinated olefin, followed by fabrication into a film and hydrolysis.
  • a cation exchange membrane prepared by ternary copolymerization of a vinyl monomer having carboxylic acid groups or precursors thereof, a vinyl monomer having sulfonic acid groups or precursors thereof and a fluorinated olefin, followed by fabrication into a film and hydrolysis.
  • Such a membrane also merely shows the intermediate characteristic.
  • cation exchange membranes prepared by forming carboxylic acid groups by chemical treatment on one surface of fluorinated cation exchange membranes having sulfonic acid groups, as disclosed by U.S. Pat. No. 4,151,053, Japanese published unexamined patent applications No. 104583/1978, No. 116287/1978 and No. 6887/1979.
  • These membranes due to the presence of carboxylic acid groups, will effectively inhibit migration and diffusion of hydroxyl ions to exhibit higher current efficiency. Also, since the carboxylic acid groups are present in the thin layer on the cathode side and sulfonic acid groups with higher water content in the residual part of the membrane, the electric resistance of the membrane is low.
  • these membranes are very excellent from the standpoint of power consumption.
  • all of these membranes while they are stably used with good performance under conventional conditions for a commercially satisfactory term, will suffer under severe conditions of further increased high current density and high temperature from swelling like splotch or formation of water bubbles, peel-off of the carboxylic acid layer from the sulfonic acid layer or formation of cracks in the carboxylic acid layer, thereby causing a decrease in current efficiency, as shown in the Comparative examples.
  • the polymeric structure of the fluorinated cation exchange membrane having sulfonic acid groups or derivatives thereof may be one of the factors for such phenomena. That is, these membranes are prepared by chemical treatment of a copolymer of a fluorinated olefin with a sulfur containing fluorinated vinylether as represented by the following formula formed in the shape of a membrane or a hydrolyzed product thereof having sulfonic acid groups: ##STR2## wherein n' is an integer of 0 to 2.
  • reaction scheme (1) For converting the cyclic sulfone to CF 2 ⁇ CFOCF 2 CF 2 SO 2 F, a number of reaction steps are required to be performed and therefore it is very difficult to produce said monomer in commercial application. Moreover, depending on the conditions, such cyclization will also occur at the time of polymerization and may lower the properties of the resultant polymer.
  • a copolymer of a fluorinated vinyl monomer having no ether linkage such as trifluorovinyl sulfonyl fluoride with tetrafluoroethylene, as disclosed by U.S. Pat. No. 3,624,053, is deficient in fabricability into a membrane.
  • X 1 is F or CF 3
  • X 2 and X 3 are F or C 1 -C 10 perfluoroalkyl
  • X 4 is F, OH, OQ 1 , OM and NQ 2 Q 3
  • Q 1 is C 1 -C 10 alkyl
  • Q 2 and Q 3 are H or one of Q 1
  • M is an alkali metal or quaternary ammonium
  • a is an integer of 0 to 3
  • b an integer of 0 or 1
  • c an integer of 0 to 12.
  • the drawing shows the change in density of the carboxylic acid groups across the thickness of the membrane of Example 19.
  • the first object of the present invention is to provide a fluorinated carboxylic acid or its derivative represented by the formula:
  • X stands for --SR 1 or --SO 2 R 2 (R 1 is an alkyl having 1 to 10 carbon atoms, an aryl, a perfluoroalkyl having 1 to 10 carbon atoms or chlorine; and R 2 is R 1 or --OM, M indicating hydrogen, a metal or ammonium group); Y stands for --COY 1 or --CN, Y 1 being halogen, hydrogen, --NH 2 , --OM (M is the same as defined above), or --OR 3 (R 3 is an alkyl having 1 to 10 carbon atoms or an aryl); and n stands for an integer of 2 to 4, and a process for producing the same.
  • the fluorinated carboxylic acid derivative according to the present invention can be prepared by converting the compound obtained by a process comprising the following step (A), (B) or (C) according to the reaction scheme (3), (4), (5) or (6), optionally in combination with various reactions such as acid treatment, hydrolysis treatment or halogenation treatment, into a carboxylic acid derivative and sulfonic acid derivative:
  • a method comprising the step to react tetrafluoroethylene with a carbonic acid ester having 3 to 20 carbon atoms in the presence of a mercaptide represented by the formula R'SM 1 (R' is an alkyl having 1 to 10 carbon atoms, an aryl or a perfluoroalkyl having 1 to 10 carbon atoms; M 1 is an alkali metal, ammonium group or a primary to quaternary alkylammonium group): ##STR7## (wherein R 4 and R 5 represent alkyl or aryl, and M 1 is the same as defined above);
  • a method comprising the step to react tetrafluoroethylene with a compound of the formula: A' 2 SO 2 (A' is a halogen or an alkoxy having 1 to 5 carbon atoms) in the presence of an alkali cyanide:
  • n may preferably be 2 when considering ease of preparation and the molecular weight of the fluorinated vinyl monomer prepared from said derivative.
  • R 1 an alkyl having 1 to 10 carbon atoms or an aryl, especially an alkyl having 1 to 10 carbon atoms is preferred. Among them, an alkyl having 1 to 5 carbon atoms is most preferred.
  • a compound wherein Y is --COF is also desirable from the standpoint of usefulness as a starting material for the synthesis of a fluorinated vinyl compound.
  • Y is another carboxylic acid derivative, such a compound may be converted to a compound having the group Y ⁇ --COF.
  • Examples of mercaptide to be used in the method (A) are derivatives of methyl mercaptan, ethyl mercaptan, propyl mercaptan, butyl mercaptan, amyl mercaptan, hexyl mercaptan, phenyl mercaptan, benzyl mercaptan, toluyl mercaptan, perfluoromethyl mercaptan, perfluoroethyl mercaptan, perfluoropropyl mercaptan, etc.
  • alkyl mercaptan in the form of sodium salts, potassium salts, cesium salts, ammonium salts, and primary to quaternary alkylammonium salts, preferably an alkyl mercaptan, especially having 1 to 5 carbon atoms, namely methyl-, ethyl-, propyl-, butyl- and amyl-mercaptan in the form of sodium salts or potassium salts.
  • the carbonic acid ester may be exemplified by dimethyl-, diethyl-, dipropyl-, dibutyl-, diphenyl-, or methylethyl-carbonate.
  • dimethyl carbonate and diethyl carbonate may be used.
  • the mercaptide and the carbonic acid ester are usually mixed in an inert medium. But no inert medium is necessarily required when said ester is liquid under the reaction conditions.
  • Typical examples of a suitable inert medium are diethyl ether, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, benzene and cyclohexane, having no active hydrogen and being capable of dissolving the carbonic acid ester.
  • the carbonic acid ester is used in an amount of 0.1 to 10 equivalents, preferably 0.5 to 5 equivalents, of the mercaptide.
  • Tetrafluoroethylene is usually employed in the gaseous state and may be fed into the reaction system under any desired pressure, irrespective of whether it may be pressurized, normal or reduced. Tetrafluoroethylene may be added in an amount of 0.1 to 5 equivalents, preferably 0.4 to 3 equivalents of the mercaptide.
  • the reaction is carried out usually at not higher than 100° C., preferably in the range from 80° to 0° C., until the pressure of tetrafluoroethylene is substantially constant under the reaction conditions employed. Formation of ketone leads to substantial decrease in the reaction yield based on the mercaptide. For this reason, it is preferred to use a lower temperature in order to suppress formation of the ketone in the reaction scheme (3).
  • the reaction is carried out under substantially anhydrous conditions.
  • the reaction system is made acidic by adding an acid.
  • an acid such as a mineral acid as hydrochloric acid, sulfuric acid or phosphoric acid is usually used, sulfuric acid being preferred.
  • the amount of mineral acid should be at least equivalent to the mercaptide initially employed.
  • ester, ketone or aldehyde which is the fluorinated carboxylic acid derivative may be performed by a conventional technique of separation such as phase separation, distillation or others.
  • Said fluorinated carboxylic acid derivative of ester, ketone or aldehyde may be converted to various carboxylic acid derivatives according to suitable organic reaction procedures.
  • ester and ketone may be hydrolyzed with an alkali to give a carboxylic acid salt, which carboxylic acid salt may in turn be treated with a mineral acid to give a carboxylic acid.
  • the above carboxylic acid or salt thereof may be reacted with a chlorinating agent such as phosphorus pentachloride, thionyl chloride, etc.
  • an acid fluoride can be prepared.
  • An acid fluoride is most useful from the standpoint of the starting material for synthesis of a fluorinated vinyl compound according to the reaction scheme (7) as shown below; ##STR9## wherein n and X are the same as defined above, and l' is 1 or 2.
  • the sulfide group present on the terminal end opposite to that of the carboxylic acid derivative group may also be converted to various derivatives according to suitable organic reaction procedures.
  • it may be converted by treatment with chlorine to the sulphenyl chloride group or sulfonyl chloride group, or by oxidation treatment to the sulfone group.
  • these groups may be subjected to hydrolysis treatment with an alkali to be converted to sulfonic acid group salts, which may be treated with phosphorus pentachloride to be converted to sulfonyl chloride groups. Conversion to such various derivative groups does not interfere with the reaction according to the scheme (7), insofar as such groups have no active hydrogen.
  • the alkali metal cyanide to be used in the method (B) may include cyanides of lithium, sodium, potassium, cesium, etc. Among them, cyanides of sodium and potassium may preferably be used.
  • Examples of the compound of the formula A' 2 SO 2 are sulfuryl fluoride, sulfuryl chloride, sulfuryl bromide, sulfuryl chlorofluoride, sulfuryl bromofluoride, dimethyl sulfate, diethyl sulfate, dibutyl sulfate, diamyl sulfate, and the like. In some cases, there may also be used sulfur dioxide.
  • the alkali metal cyanide is used usually as a dispersion in an inert medium.
  • an inert medium When the compound A' 2 SO 2 (A' is the same as defined above) is a liquid under the reaction conditions, no such inert medium is necessarily required to be used.
  • solvents having no active hydrogen such as diethyl ether, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, benzene, cyclohexane, etc.
  • Said inert medium may desirably be capable of dissolving A' 2 SO 2 .
  • the A' 2 SO 2 is used in an amount of 0.1 to 10 equivalents, preferably 0.5 to 5 equivalents of the alkali metal cyanide.
  • A' 2 SO 2 is previously charged in the reaction system to be mixed with the alkali metal cyanide, or fed into the reaction system simultaneously with tetrafluoroethylene, or fed into the reaction system previously mixed with tetrafluoroethylene.
  • Tetrafluoroethylene is used usually under the gaseous state and may be fed into the reaction system under any desired pressure, whether it may be pressurized, reduced or normal.
  • Tetrafluoroethylene is added in an amount of 0.1 to 5 equivalents, preferably 0.4 to 3 equivalents of the alkali metal cyanide.
  • the reaction is carried out at not higher than 250° C., preferably at not higher than 100° C., until the pressure of tetrafluoroethylene is substantially constant under the reaction conditions employed.
  • the reaction is conducted under substantially anhydrous conditions.
  • Separation of fluorinated nitrile may be performed according to such procedures as phase separation or distillation. Similarly as described in the method (A), said fluorinated nitrile may be converted to various carboxylic acid derivatives or sulfonic acid derivatives according to suitable organic reaction procedures, whereby it is most preferred that Y should be --COF.
  • the compound represented by the formula Z'SO 2 F or Z' 3 CSO 2 F (Z' is the same as defined above) to be used in the method (C) may be exemplified by sulfuryl chlorofluoride, sulfuryl bromofluoride, trichloromethane sulfonylfluoride, tribromomethane sulfonylfluoride, and the like. Among them, sulfuryl chlorofluoride and trichloromethane sulfonylfluoride are preferred.
  • the free radical initiator there may be employed most of those conventionally used in the field of organic chemical reactions.
  • organic peroxides such as benzoyl peroxide, di-t-butyl peroxide, perfluoroacetyl peroxide, di-t-amyl peroxide, etc. and azo-bis type compounds such as azobisisobutyronitrile, azobisisovaleronitrile, azobisnitrile, etc.
  • ultra-violet irradiation instead of permitting the free radical initiator to be present in the reaction, ultra-violet irradiation may be employed. Alternatively, it is also possible to effect irradiation of ultra-violet rays in the presence of a free-radical initiator.
  • a solvent is not particularly limited, but there may be employed any solvent which is stable chemically to the free radical initiator or ultra-violet rays. Particularly, 1,1,2-trichloro-1,2,2-trifluoroethane and cyclohexane may preferably be used.
  • Tetrafluoroethylene is used in at least a stoichiometric amount relative to Z'SO 2 F or Z' 3 CSO 2 F.
  • the amount of the free radical initiator used is in the range from 0.001% to 10% based on Z'SO 2 F or Z' 3 CSO 2 F.
  • the reaction temperature may suitably be determined in view of the half-life period of the free radical initiator or other factors, usually ranging from -10° C. to 250° C., preferably from 0° C. to 150° C.
  • the intermediates formed according to the reaction scheme (5) or (6) are isolated by phase separation or distillation from the reaction mixture, if desired.
  • Said intermediates may be subjected to acid treatment using a mineral acid such as conc. sulfuric acid, sulfuric anhydride or fuming nitric acid to be converted to HOOC(CF 2 ) 3 SO 2 F or HOOC(CF 2 ) 4 SO 2 F.
  • the above carboxylic acid may be isolated from the reaction mixture by an isolation procedure such as extraction, phase separation or distillation. Similarly as described in the method (A), said carboxylic acid may be converted to various carboxylic acid derivatives according to suitable organic chemical reaction procedures. It is particularly preferred that Y should be --COF. Among various sulfonic acid derivatives, sulfonylfluoride groups can be converted to sulfone and sulfide groups.
  • a compound having a sulphenylchloride group and sulphenyliodide group may be allowed to react with tetrafluoroethylene in the presence of a free radical initiator, followed by treatment of the resultant intermediate with an acid such as conc. sulfuric acid, sulfuric anhydride or fuming nitric acid, to provide the compound of the present invention having both a sulfide group and carboxylic acid group.
  • the compound of the present invention is very useful for synthesis of a fluorinated vinyl ether compound having terminal groups convertible to sulfonic acid groups as shown in the reaction scheme (7).
  • the above compound is also useful as starting materials for production of various materials such as surfactants, fiber treatment agents, lubricants, agricultural chemicals, etc.
  • the fluorinated carboxylic acid derivative of the present invention can also very advantageously be produced, since no dangerous reaction is used such as the addition reaction between tetrafluoroethylene and SO 3 which will occur in the production of FSO 2 CF 2 COF and also no toxic compound such as a cyclic sultone intermediate is involved.
  • the second object of the present invention is to provide a novel fluorinated acid fluoride represented by the formula: ##STR10## wherein X' is --SR or SO 2 R (R is C 1 -C 10 alkyl, C 1 -C 10 perfluoroalkyl, aryl or chlorine), n is an integer of 2 to 4, p is an integer of 0 to 50, and a process for producing said fluorinated acid fluoride compound which comprises reacting a novel compound represented by the formula:
  • the fluorinated acid fluoride of the present invention can be produced according to the following reaction scheme: ##STR12## wherein X', n and p are the same as defined above.
  • the reaction between the compound of the formula X'(CF 2 ) n COF (wherein X' and n are the same as defined above) and hexapropylene oxide may preferably be conducted in the presence of a fluoride ion as catalyst.
  • a fluoride ion as catalyst.
  • a suitable fluoride including alkali metal fluorides such as cesium fluoride, potassium fluoride, etc.; silver fluoride; ammonium fluoride; C 1 -C 4 tetraalkyl ammonium fluoride such as tetramethyl ammonium fluoride, tetraethyl ammonium fluoride and tetrabutyl ammonium fluoride; and so on.
  • the fluoride catalyst is usually used together with an inert liquid diluent, preferably an organic liquid, which can dissolve at least 0.001% of the fluoride selected.
  • the fluoride catalyst may be used in an amount of about 0.01 to about 2 mole equivalent per one mole of the compound represented by the formula X'(CF 2 ) n COF wherein X' and n are the same as defined above.
  • suitable diluents are polyethers such as ethyleneglycol dimethylether, diethyleneglycol dimethylether, tetraethyleneglycol dimethylether, etc. and nitriles such as acetonitrile, propionitrile, etc.
  • the reaction is slightly exothermic and therefore there should be provided a means for dissipating the reaction heat.
  • the reaction temperature may be in the range from about -50° C. to about 200° C., preferably from about -20° C. to about 150° C.
  • the pressure is not a critical parameter and may either be lower than or not lower than the atmospheric pressure.
  • the reaction time may usually be from 10 minutes to 100 hours.
  • the applicable molar ratio of hexapropylene oxide to X'(CF 2 ) n COF is from about 1/20 to about 100/1.
  • the compound ##STR13## has a low p value, for example, when p is 0 or 1, the relative proportion of X'(CF 2 ) n COF is increased, and lower pressure and higher temperature are preferred to be selected.
  • a cation exchange membrane prepared from a copolymer of said fluorinated vinyl ether compound and tetrafluoroethylene may desirably have an ion-exchange capacity as large as possible.
  • said fluorinated vinyl ether compound may preferably have a molecular weight as small as possible. Accordingly, it is preferred that the value of p may be 0 or 1, most preferably 0.
  • the compound represented by the formula: ##STR15## wherein X', n and p are the same as defined above is useful as an intermediate for the preparation of a novel fluorinated vinylether compound having functional groups convertible to sulfonic acid groups. Said compound is also useful as a starting material for surfactants, fiber treatment agents, lubricants, agricultural chemicals, etc.
  • the third object of the present invention is to provide a novel fluorinated vinylether compound represented by the formula: ##STR16## wherein X' is --SR or SO 2 R (R is C 1 -C 10 alkyl, an aryl, C 1 -C 10 perfluoroalkyl or chlorine, n an integer of 2 to 4 and p' an integer of 0 to 5, and a process for preparing the same.
  • the fluorinated vinylether compound of the present invention can be prepared according to the following reaction schemes: ##STR18## wherein X', n and p' are the same as defined above and W is F or OM' (M' is an alkali metal).
  • Said reaction can be practiced under substantially anhydrous conditions under either pressurized, normal or reduced pressure. Usually, however, the reaction may conveniently be practiced under normal or reduced pressure.
  • a diluent to a dilution degree of 0 to 100 depending on the mode of reaction, said diluent being selected from inert gases such as nitrogen, helium, carbon dioxide, argon, etc. or inert non-protonic liquids such as polyethers.
  • the terminal group is an acid fluoride group
  • a solid base which can decompose any corrosive and toxic COF 2 generated such as sodium carbonate, potassium carbonate, sodium phosphate, potassium phosphate, etc.
  • the reaction temperature may range from 100° to 600° C., preferably from 100° to 350° C. If the temperature is too high, side reactions such as decomposition other than vinylization are liable to occur. At too low a temperature, conversion of the starting material is lowered.
  • the reaction time may be from 0.1 second to 10 hours, preferably from 10 seconds to 3 hours. The reaction temperature and the reaction time should suitably be selected to provide optimum conditions, for example, shorter reaction time at higher reaction temperature or longer reaction time at lower reaction temperature.
  • R may preferably be C 1 -C 10 alkyl or an aryl, especially C 1 -C 10 alkyl, most preferably C 1 -C 5 alkyl.
  • the cation exchange membrane to be prepared from the copolymer of said fluorinated vinylether compound and tetrafluoroethylene is desired to have an ion-exchange capacity as large as possible.
  • the fluorinated vinylether compound of the present invention can be copolymerized with, for example, tetrafluoroethylene to give a fluorinated cation exchange membrane which has the very excellent characteristic of sufficiently high ion-exchange capacity while maintaining good mechanical strength.
  • the fluorinated vinylether compound of the present invention may also be useful as an intermediate for synthesis of various fluorinated compounds having functional groups containing a sulfur atom at the terminal end of the molecule, for example, surfactants, fiber treating agents, lubricants, etc. It is also possible to prepare a fluorinated elastomer comprising a copolymer of the above fluorinated vinylether compound with a fluorinated olefin using said compound as a constituent or crosslinking monomer of said elastomer.
  • the fourth object of the present invention is to provide a novel fluorinated copolymer comprising the following recurring units (A) and (B):
  • the ratio of the numbers of recurring unit (A)/(B) is desired to be in the range from 1 to 16.
  • the recurring unit (A) in the above formula may preferably be: ##STR27## (L is F, Cl, CF 3 , --OR F or H, R F being the same as defined above). It is particularly preferred that L should be F.
  • the notation k may preferably be zero.
  • the ratio (A)/(B) is preferred to be in the range from 1.5 to 14, more preferably from 3 to 11.
  • l should be equal to 3 and R should be C 1 -C 10 alkyl or an aryl, C 1 -C 10 alkyl being especially preferred.
  • R should be C 1 -C 10 alkyl or an aryl, C 1 -C 10 alkyl being especially preferred.
  • the above copolymer is substantially a random copolymer having a molecular weight generally in the range from 8,000 to 1,000,000, having a melt index generally in the range from 0.001 g/10 min. to 500 g/10 min., as measured by use of an orifice of 2.1 mm in diameter and 8 mm in length, under a load of 2.16 kg at 250° C.
  • the above copolymer may conveniently be identified by measurement of the infrared absorption spectrum (IR) or attenuated total reflection (ATR) of a film of the copolymer, as shown in the Examples.
  • IR infrared absorption spectrum
  • ATR attenuated total reflection
  • composition of the copolymer is estimated by measurement of the ion-exchange capacity, elemental analysis or a combination thereof after converting all of the sulfur containing terminal groups to ion-exchange groups such as sulfonic acid groups or carboxylic acid groups.
  • the structure of the pendant groups contained in the copolymer according to the present invention can also be identified by measurement of the IR or ATR of the product formed by converting the sulfur containing terminal groups to ion-exchange groups such as sulfonic acid groups, carboxylic acid groups or sulfinic acid groups and then carrying out the reaction for elimination of said ion-exchange groups.
  • ion-exchange groups such as sulfonic acid groups, carboxylic acid groups or sulfinic acid groups
  • the fluorinated copolymer of the present invention can be prepared by copolymerization of at least one monomer selected from the group consisting of the olefins of the formula:
  • a 1 , A 2 , A 3 and A 4 are the same as defined above, at least one monomer selected preferably from the group consisting of the fluorinated olefins of the formula:
  • L is F, Cl, CF 3 , --OR F or H, R F being C 1 -C 5 perfluoroalkyl, and at least one monomer selected from the group consisting of sulfur containing fluorinated vinylether compounds of the formula: ##STR28## wherein k, l, Z and R are the same as defined above.
  • the fluorinated olefin to be used in the present invention may preferably be one containing no hydrogen atom from the standpoint of heat resistance and chemical resistance of the resultant copolymer. Above all, tetrafluoroethylene is most preferred.
  • the group R may preferably be C 1 -C 10 alkyl or an aryl in view of the ease in preparation of the vinyl monomer. Among them, C 1 -C 10 alkyl group is more preferable.
  • Typical examples of the sulfur containing fluorinated vinylether compounds preferably used in the present invention are as follows: ##STR29## wherein k is 0 or 1, preferably 0, R is C 1 -C 10 alkyl or an aryl.
  • the content of fluorinated olefin can be increased at the same level as the ion-exchange capacity of the membranes or resins, whereby there can be obtained membranes or resins having higher ion-exchange capacity and also having good physical toughness.
  • the ratio of the olefin and the sulfur containing fluorinated vinyl ether compound to be copolymerized can be controlled by suitable selection of the ratio of monomers charged and the polymerization conditions.
  • the copolymer of the present invention may be prepared according to well known polymerization methods used for homopolymerization or copolymerization of a fluorinated ethylene.
  • the methods for preparation of the copolymer of the present invention may include both a method in which polymerization is conducted in a non-aqueous system and a method in which polymerization is conducted in an aqueous system.
  • the polymerization temperature may generally range from 0° to 200° C., preferably from 20° to 100° C.
  • the pressure may be from 0 to 200 kg/cm 2 , preferably from 1 to 50 kg/cm 2 .
  • the non-aqueous polymerization may frequently be carried out in a fluorinated solvent.
  • Suitable non-aqueous solvents may include inert 1,1,2-trichloro-1,2,2-trifluoroethane or perfluoro-hydrocarbons, e.g. perfluoromethylcyclohexane, perfluorodimethylcyclobutane, perfluorooctane, perfluorobenzene, etc.
  • an aqueous polymerization method for preparation of the copolymer there may be mentioned an emulsion polymerization method wherein monomers are brought into contact with an aqueous medium containing a free radical initiator and an emulsifier to provide a slurry of polymer particles or a suspension polymerization method wherein monomers are brought into contact with an aqueous medium containing both free radical initiator and dispersion stabilizer inert to telomerization to provide a dispersion of polymer particles, followed by precipitation of the dispersion.
  • the free radical initiator to be used in the present invention there are redox catalysts such as ammonium persulfate-sodium hydrogen sulfite, etc.; organic peroxides such as t-butyl peroxide, benzoyl peroxide, etc.; azo-bis type compounds such as azobisisobutyronitrile, and fluorine radical initiators such as N 2 F 2 , etc.
  • redox catalysts such as ammonium persulfate-sodium hydrogen sulfite, etc.
  • organic peroxides such as t-butyl peroxide, benzoyl peroxide, etc.
  • azo-bis type compounds such as azobisisobutyronitrile
  • fluorine radical initiators such as N 2 F 2 , etc.
  • the polymer may be molded into membranes or granules, if desired.
  • a conventional technique may be used for molding the polymer into a thin film or pellets by melting the polymer.
  • the copolymer of the present invention is useful as a starting material for preparation of a fluorinated cation exchange membrane having sulfonic acid groups and/or carboxylic acid groups.
  • the above membrane may, sometimes preferably, be laminated with a membrane made from a copolymer having a greater copolymerization ratio of the sulfur containing fluorinated vinylether compound.
  • the membrane to be laminated there may be used a membrane prepared from the copolymer of the monomers selected from the group of the above sulfur containing fluorinated vinylether compounds and the groups of fluorinated olefins.
  • the membrane to be used for lamination may preferably have a thickness of 1/2 to 19/20 times the thickness of the entire laminated product in order to make the electric resistance thereof smaller.
  • the above membrane can be reinforced in strength by backing with a mechanical reinforcing material such as a net.
  • a mechanical reinforcing material such as a net.
  • backing materials there may most suitably be used a net made of polytetrafluoroethylene fibers.
  • a porous polytetrafluoroethylene sheet is also useful.
  • the reinforcing material may preferably be embedded on the side of the membrane with the greater copolymerization ratio of sulfur containing fluorinated vinylether compound.
  • Reinforcing materials may be embedded in the membrane by a method such as laminating, press contact embedding or vacuum fusion embedding. For example, when a net is to be embedded, a membrane is placed on a net and the surface of the membrane opposite to that contacted with the net is heated to a temperature no higher by 20° C.
  • the surface of the membrane contacted with the net maintained at a temperature higher by at least 60° C. than the melting point of the membrane, while providing a pressure difference between both sides of the membrane.
  • the pressure on the side contacted with the net is made lower than the opposite side.
  • the thickness of the membrane is generally 2500 microns or less, preferably 1000 microns or less, more preferably 500 microns or less.
  • the lower limit is restricted by the mechanical strength required, but usually 10 microns or more.
  • the copolymer of the present invention may be formed into particles during polymerization or molding according to conventional procedures for preparation of ion-exchange resins, and then subjected to the reaction used for converting a membrane into a fluorinated cation exchange membrane to provide fluorinated ion-exchange resin particles.
  • ion-exchange resins can be processed into any desired shape such as granules, membranes, fibers, strands, etc.
  • heat resistance and chemical resistance superior to hydrocarbon type resins they are useful generally in separation processes which one based on adsorption properties such as adsorptive separation of metallic ions or separation of organic high molecular substances. They are also useful as acid catalysts for organic reactions.
  • copolymer according to the present invention can also be used in the form of fibers or strands as ion-conductive reinforcing material for a fluorinated cation exchange membrane.
  • Said copolymer may also be blended with other fluorocarbon type or hydrocarbon type copolymers to provide various blends useful for various purposes. It may also be provided as it is or as a mixture with a suitable solvent for use as lubricants, surfactants, etc. It is also useful as the starting material for a fluorinated elastomer.
  • the fifth object of the present invention is to provide a novel fluorinated cation exchange membrane for use in electrolysis of an aqueous alkali metal halide solution, comprising the following recurring units (C), (D) and (E): ##STR32## (L is F, Cl, CF 3 , OR F or H, R F being C 1 -C 5 perfluoroalkyl) ##STR33## (k is 0 or 1, l is an integer of 3 to 5, M is H, metal or ammonium ion); ##STR34## (k and M are the same as defined above and m is (l-1), and having a carboxylic acid group density, which is defined as the percentage of the number of carboxylic acid groups based on the total number of all ion-exchange groups present in a layer substantially parallel to the surfaces of the membrane, of at least 20% on one surface of the membrane, said carboxylic acid group density being gradually decreased toward the innerside of the membrane from said one surface of the membrane, and also a process for producing
  • the relative proportion of the recurring units (C)/[(D)+(E)] may preferably be in the range from 1.5 to 14. It is also preferred that the density of carboxylic acid groups across the membrane should be decreased moderately enough such that the gradient in terms of the decreased percentage of carboxylic acid groups per unit thickness may be 20%/micron at its maximum.
  • One specific feature of the membrane according to the present invention resides in having excellent electrolysis performance of high current efficiency and low electrolysis voltage. Another specific feature of the membrane resides in stability under more severe conditions than those usually employed, whereby said excellent electrolysis performance can be maintained for a long time. The membrane can also be produced economically with ease and at low cost.
  • the excellent electrolysis performance of the membrane according to the present invention may be ascribed to the specific structure of the membrane, having a carboxylic acid group density on one surface of 20% to 100%, preferably 40% or more, more preferably 60% or more, said carboxylic acid group density gradually decreasing from said one surface toward the innerside of the membrane, i.e. in the direction of thickness of the membrane.
  • the maximum gradient should preferably be 20 to 0.1% per one micron of the membrane thickness, more preferably 10% to 1%.
  • said carboxylic acid group density may reach substantially zero % at a depth of not more than 1/2 of the entire thickness of the membrane from one surface.
  • the carboxylic acid groups should preferably be present in the membrane locally in one half side of the membrane, being more enriched with a gradual increase the nearer to the surface on one side, while the other half side of the membrane contains other exchange groups, namely sulfonic acid groups.
  • the depth at which the carboxylic acid group density reaches zero % may be less than 1/2 of the entire thickness of the membrane, i.e. 1/4 or less, most preferably 1/6 or less, to the lower limit of about 1 ⁇ .
  • the membrane of the present invention When the membrane of the present invention is used for electrolysis of an aqueous alkali metal halide solution, it is preferred to use the membrane with the surface having higher carboxylic acid group density facing toward the cathode. With such an arrangement, said surface shrinks when contacted with a highly concentrated alkali due to the presence of carboxylic acid groups to increase the concentration of fixed ions. As the result, permeation, migration and diffusion of hydroxyl ions into the membrane can effectively be inhibited, whereby high current efficiency can be exhibited.
  • the carboxylic acid group density on said one surface of the membrane may be variable depending on various factors such as the value of the ratio (C)/[(D)+(E)], the current density, the temperature and the alkali concentration employed in electrolysis and can be optimally determined by controlling the conditions in preparation. Generally speaking, as the value of (C)/[(D)+(E)] is greater, the carboxylic acid group density may be lower.
  • carboxylic acid groups are present primarily in a thin layer on the side of one surface of the membrane, only sulfonic acid groups being present in most of the residual portion. For this reason, the electric resistance in migration of alkali metal ions from the anode chamber to the cathode chamber is extremely low as compared with, for example, a membrane containing only carboxylic acid groups.
  • the membrane Due to the presence of sulfonic acid groups, the water content in the membrane as a whole is also very large as compared with a membrane containing only carboxylic acid groups and therefore the membrane can be free from hardening or embrittlement due to shrinkage of the membrane even when used under severe conditions in a highly concentrated alkali for a long term.
  • the membrane of the present invention can be used more stably than the membrane of the prior art even under more severe conditions than those conventionally used may be ascribed to the specific structure of the polymer substantially consisting of the recurring units (C), (D) and (E) as described above.
  • the suffix k should be equal to zero, but there may also be partially mixed therewith a polymer wherein k is one. It is also preferred from the ease of preparation of the monomer, the physical properties of the resultant polymer and greater variable range of the polymer properties that the suffix l should be equal to 3.
  • a membrane with an l value of 6 or more is inferior to those with l values of 3 to 5 from the standpoint of difficulty in commercial production of the monomer and insufficient ion-exchange capacity obtained.
  • a membrane wherein L is a fluorine atom is particularly preferred from the aspects of heat resistance and chemical resistance.
  • the above monomer is different in the structure of the terminal end or in the number of members of the ring in the product by-produced in the vinylization step, as compared with the sulfur containing fluorinated vinylether of the formula: ##STR36## wherein n' is an integer of 0 to 2, which is used as starting material for a sulfonic acid type membrane of the prior art or a sulfonic acid type membrane having been formed by chemical treatment of carboxylic acid groups in the surface stratum thereof, and therefore it is possible to form substantially no or to decrease to a great extent the cyclization reaction in the vinylization step as mentioned above.
  • the resultant polymer can have a structure containing substantially no or only a very small proportion of pendant groups: ##STR37## Consequently, with the same level of the ion-exchange capacity, the content of fluorinated olefin can be increased. In other words, there can be produced a physically tough membrane with enhanced ion-exchange capacity. Moreover, while its mechanism has not yet been clarified, such a membrane can maintain stable performance, being prevented from encountering problems of peel-off or crack of the carboxylic acid layer, even when used under more severe conditions than those conventionally used.
  • the membrane of the present invention is stable under severe conditions
  • the relative ratio of the recurring units (C), (D) and (E) i.e. the ratio of (C)/[(D)+(E)] which is generally in the range from 1.5 to 14, preferably from 3 to 11, more preferably from 3.5 to 6.
  • the ratio is less than 1.5, the membrane is liable to be swelled during usage and therefore cannot maintain stable performance for a long term.
  • the membrane is liable to shrink so as to make the electric resistance of the membrane impractically high.
  • the swelling and shrinking behavior of a membrane with a given species of ion-exchange groups is not controlled by the ion-exchange capacity per se of the membrane but by the most important factors including the fluorinated olefin constituting the copolymer, the copolymer ratio of the fluorinated vinylether having ion-exchange groups and the presence or absence of ##STR38##
  • the fluorinated olefin constituting the copolymer the copolymer ratio of the fluorinated vinylether having ion-exchange groups and the presence or absence of ##STR38##
  • a fluorinated vinylether having no ##STR39## groups as principal components and to control the above copolymerization ratio within a certain range.
  • the ion-exchange capacity as represented by the above formula is based on such considerations.
  • the membrane according to the present invention it is possible to provide a structure containing substantially no or a small amount of pendant groups: ##STR40##
  • the copolymerization ratio of tetrafluoroethylene can be increased in the membrane of the present invention, as compared with a membrane prepared by use of ##STR41## as a sulfur containing fluorinated vinylether, thereby providing a membrane having both high ion-exchange capacity and good physical toughness.
  • the membrane of the present invention is specific in having a carboxylic acid group density which is gradually decreased from the surface to the innerside, preferably at a gradient within a specific range. This is still another reason why the membrane of the present invention is by far more stable than the membrane of the prior art under more severe conditions than those conventionally used.
  • the membrane having a laminated structure comprising a membrane containing carboxylic acid groups and a membrane containing sulfonic acid groups, as disclosed by Japanese published unexamined patent applications No. 36589/1977 and No. 132089/1978, is incomplete in bonding as previously mentioned and liable to cause peel-off or water bubbles in a short period of time at the laminated portion.
  • the membrane of the present invention can maintain stable performance for by far a longer time than the membranes of the prior art without causing abnormal phenomena such as peel-off or crack of the carboxylic acid layer even under the conditions of a high current density of 110 A/dm 2 and a high temperature of 95° C. or higher.
  • Such a structure is also preferred from the standpoint of lowering the electric resistance of a membrane.
  • p" may be equal to zero and q equal to l.
  • the thickness of the fluorinated cation exchange membrane comprising the recurring unit (F) may have a thickness 1/2 to 19/20 as thick as the entire membrane.
  • the membrane of the present invention may also be provided with a backing with a mechanical reinforcing material such as a net for the purpose of increasing the strength of the membrane.
  • a mechanical reinforcing material such as a net for the purpose of increasing the strength of the membrane.
  • a net made from polytetrafluoroethylene fibers is most suitable, but there may also be used a porous polytetrafluoroethylene sheet. It is also possible to incorporate fibrous polytetrafluoroethylene during molding of a membrane for increasing the strength thereof.
  • the membrane of the fluorinated copolymer used for preparation of the membrane of the present invention can be produced according to the method as previously described. Then, as the second step, a part or all of the terminal groups of the recurring unit (G) of a membrane prepared by the method as mentioned above comprising essentially the recurring units (C) and (G) as shown below: ##STR43## (L is the same as defined above) ##STR44## (k, l, Z and R are the same as defined above) are converted, if necessary, to sulfonylchloride groups --CF 2 SO 2 Cl or sulfonylbromide groups --CF 2 SO 2 Br, preferably sulfonylchloride groups using a halogenating agent represented by the formula:
  • the reaction used in this step is different depending on the types of Z and R. Details of each reaction are set forth below for each type.
  • chlorine may preferably be used.
  • --CF 2 SO 2 Cl is formed directly or via --CF 2 SCl.
  • the reaction conditions may be variable within a broad range, but the reaction temperature is generally from 0° to 300° C. under normal pressure or under pressurization.
  • the chlorine employed may either be in the dry state or in a solution dissolved in water, an organic solvent such as acetic acid, trichloroacetic acid, trifluoroacetic acid, or an inorganic solvent such as S 2 Cl 2 .
  • Said oxidation treatment may be conducted usually in an aqueous solution at 20° to 200° C., whereby an organic solvent such as acetic acid or trichloroacetic acid may also be present in the solution to accelerate permeation of the oxidizing agent into the membrane.
  • the sulfoxide formed by the above oxidation treatment may be converted to --CF 2 SO 2 Cl with chlorine.
  • the hydrolysis may be carried out using a solution of caustic soda or caustic potash dissolved in water, a mixed solvent of water with an organic solvent such as alcohol or dimethylsulfoxide, optionally containing an oxidizing agent added, for example, at 20° to 200° C.
  • sulfonic acid groups may easily be converted to sulfonylchloride groups by reaction with vapors of phosphorus pentachloride or a solution of phosphorus pentachloride dissolved in phosphorus oxychloride, an organic halide compound, etc. according to the method and conditions as described in Japanese published unexamined patent applications No. 134888/1977 and No. 4289/1979.
  • a mixture of phosphorus trichloride with chlorine may also be used.
  • Such a conversion can be accomplished by treatment of a membrane comprising the recurring units (C) and (H) with a reducing agent and according to the reaction method and reaction conditions as generally described in Japanese published unexamined patent applications No. 24176/1977, No. 24177/1977 and No. 132094/1978, thereby converting --CF 2 -- directly bonded to sulfur atom directly or via sulfinic acid groups into carboxylic acid groups.
  • a specific structure of m (l-1) in the pendant groups of the recurring units (E).
  • the reducing agents to be used in the present invention may preferably be selected from acids having reducing ability such as hydroiodic acid, hydrobromic acid, hypophosphorous acid, hydrogen sulfide water, arsenous acid, phosphorous acid, sulfurous acid, nitrous acid, formic acid, oxalic acid, etc., their metal salts, ammonium salts, and hydrazines, from the standpoint of reactivity and ease in handling. Among them, an inorganic acid having reducing ability is most preferred. These reducing agents may be used alone or, if necessary, as a mixture.
  • the structure of the membrane comprising carboxylic acid groups enriched on only one surface of the membrane which is the excellent specific feature of the membrane according to the present invention, may be realized easily by applying the second step reaction or preferably the third step reaction on one surface of the membrane. In case of a membrane having a laminated structure, these reactions may be applied on the surface opposite to that on which lamination is effected.
  • the gradient of the carboxylic acid group density may be controlled to a desired shape of the density curve by adequately controlling various factors in the reactions in the second or the third step such as temperature, time, pressure, solvent composition, etc. to thereby balance the reaction rate and the diffusion velocity of a reagent into the membrane. For ease of control, it is preferred to effect such controlling in the third step.
  • a method for controlling the carboxylic acid group density there may be mentioned a method wherein the above treatment with a reducing agent is effected in the presence of at least one organic compound having 1 to 12 carbon atoms selected from alcohols, carboxylic acids, sulfonic acids, nitriles or ethers, using especially a solution of said organic compounds dissolved in an aqueous reducing agent solution.
  • carboxylic acids may preferably be used as such organic compounds.
  • These organic compounds may be added in an amount, which is variable depending on the membrane employed, the reducing agent and organic compound employed as well as the reaction conditions and may suitably be selected within the range of 100 ppm or more.
  • alcohols to be used in the present invention may include methanol, ethanol, propanol, ethylene glycol, diethylene glycol, 1,4-butane diol, 1,8-octane diol, glycerine, and the like.
  • carboxylic acids and sulfonic acids there may be mentioned formic acid, acetic acid, propionic acid, butyric acid, iso-butyric acid, n-valeric acid, caproic acid, n-heptanoic acid, caprylic acid, lauric acid, fluoroacetic acid, chloroacetic acid, bromoacetic acid, dichloroacetic acid, malonic acid, glutaric acid, trifluoroacetic acid, perfluoropropionic acid, perfluorobutyric acid, perfluorovaleric acid, perfluorocaproic acid, perfluoro-n-heptanoic acid, perfluorocaprylic acid, perfluoroglutaric acid, trifluoromethane sulfonic acid, perfluoroheptane sulfonic acid, methane sulfonic acid, ethane sulfonic acid, propane sulfonic acid, butane sulfonic
  • nitriles are acetonitrile, propionitrile, adiponitrile, and the like.
  • Ethers may be exemplified by diethylether, tetrahydrofuran, dioxane, ethylene glycol dimethylether, diethylene glycol dimethyl ether, etc.
  • organic compounds some compounds may undergo chemical changes depending on the reducing agent employed and therefore it is desired to avoid such a combination.
  • the gradient of the carboxylic acid group density in the membrane may be determined, as illustrated in the Examples, by staining the cross-section of a membrane with a suitable dye and observing the result of staining, or alternatively by scraping the membrane substantially in parallel to the surface thereof (usually in a thickness of about 1 to 5 micron per each scraping), subjecting the scraped face to attenuated total reflection (hereinafter referred to as ATR) and calculating from the changes in intensity of the absorption peak based on the carboxylic acid groups.
  • ATR attenuated total reflection
  • the pendant structure having bonded ion-exchange groups can be identified by measurement of ATR or IR absorption spectrum after the reaction for elimination of ion-exchange groups.
  • the membrane comprising the recurring units (G) may be irradiated with ultra-violet rays or an electron beam to be directly converted to carboxylic acid groups. It is also possible to obtain a membrane containing carboxylic acid groups with more --CF 2 -- than that obtained by use of a reducing agent, i.e.
  • Said method comprises reacting a membrane having sulfonyl halide groups or a membrane having sulfinic acid groups or --CF 2 I obtained as intermediate in the method as described above with a compound having carbonyl groups or unsaturated bonding under the conditions to eliminate SO 2 or iodine atom ionically or radically.
  • any of said alternative methods is inferior to the method wherein a reducing agent is used.
  • a reducing agent is used in preparation of a membrane to be used under more severe conditions than those conventionally used.
  • the fourth step for preparation of the membrane of the present invention is to convert all of the residual sulfur containing terminal groups to sulfonic acid groups. This can easily be done according to the reaction as mentioned in the second step reaction or by application of the reactions such as oxidation, hydrolysis, etc. as described in Japanese published unexamined patent applications No. 24176/1977 and No. 24177/1977.
  • the membrane of the present invention can be derived from common starting materials according to simple reactions to have carboxylic acid groups and sulfonic acid groups.
  • the membrane can be manufactured easily and advantageously at low cost.
  • the cation exchange membrane according to the present invention may favorably be employed in electrolysis of an aqueous alkali metal halide solution. That is, the membrane of the present invention is useful not only in electrolysis of an alkali metal halide under conventional electrolysis conditions, i.e. a current density of 10 to 70 A/dm 2 , a temperature of 20° to 100° C., alkali metal halide concentration of 1 to 5 N and an alkali concentration of 1 to 15 N, but is also useful under severe conditions, i.e. a current density of 70 to 200 A/dm 2 and a temperature of 100° to 150° C., with stable performance for a long time.
  • conventional electrolysis conditions i.e. a current density of 10 to 70 A/dm 2 , a temperature of 20° to 100° C., alkali metal halide concentration of 1 to 5 N and an alkali concentration of 1 to 15 N
  • severe conditions i.e. a current density of 70 to 200 A/dm 2
  • the sixth object of the present invention is to provide a novel fluorinated cation exchange membrane containing sulfonic acid groups, comprising essentially the following units (I) and (J):
  • the above sulfonic acid type cation exchange membrane can be prepared by use of the membrane of the aforesaid fluorinated copolymer as described above. Said membrane can be treated by application of the reactions as described above to convert all of the sulfur containing terminal groups into sulfonic acid groups to give the novel cation exchange membrane containing sulfonic acid groups comprising the recurring units (I) and (J) as defined above.
  • This membrane is useful in various fields such as electrolysis of an aqueous alkali metal halide solution, electrolysis of water, diaphragms for fuel cells, etc. For the reason mentioned below, this membrane is superior to fluorinated cation exchange membranes containing sulfonic acid groups conventionally used in commercial application.
  • the specific feature in performance of the sulfonic acid type membrane according to the present invention is based on the specific structure of the sulfur containing fluorinated vinylether of the following formula used for preparation of said sulfonic acid type membrane ##STR47## wherein k, l, Z and R are the same as defined above.
  • the above monomer is different in the structure of the terminal end or in the number of members of the ring, as compared with the sulfur containing fluorinated vinylether of the formula: ##STR48## wherein n' is 0 to 2, which is used as starting material for a sulfonic acid type membrane of the prior art, and therefore it is possible to form substantially no or to decrease to a great extent the cyclization reaction in the vinylization step as mentioned above.
  • the resultant polymer can have a structure containing substantially no or only a very small proportion of pendant groups: ##STR49## Consequently, with the same level of the ion-exchange capacity, the content of fluorinated olefin can be increased. In other words, there can be produced a physically tough membrane with enhanced ion-exchange capacity.
  • the membrane of the present invention is stable under severe conditions
  • the relative ratio of the recurring units (I) and (J) i.e. the ratio of (I)/(J) which is generally in the range from 1.5 to 14, preferably from 3 to 11, more preferably from 3.5 to 6.
  • the ratio is less than 1.5, the membrane is liable to swell during usage and therefore cannot maintain a stable performance for a long term.
  • the membrane is liable to shrink so as to make the electric resistance of the membrane impractically high.
  • the swelling and shrinking behavior of a membrane with a given species of ion-exchange groups is not controlled by the ion-exhange capacity per se of the membrane but by the most important factors including the fluorinated olefin constituting the copolymer, the copolymer ratio of the fluorinated vinylether having ion-exchange groups and the presence or absence of ##STR50##
  • the fluorinated olefin constituting the copolymer the copolymer ratio of the fluorinated vinylether having ion-exchange groups and the presence or absence of ##STR50##
  • a fluorinated vinylether having no ##STR51## group as principal component and to control the above copolymerization ratio within a certain range.
  • the ion-exchange capacity as represented by the above formula is based on such considerations.
  • the membrane according to the present invention it is possible to provide a structure containing substantially no or only a small amount of pendant groups: ##STR52##
  • the copolymerization ratio of tetrafluoroethylene can be increased in the membrane of the present invention, as compared with a membrane prepared by use of ##STR53## as a sulfur containing fluorinated vinylether, thereby providing a membrane having both high ion-exchange capacity and good physical toughness.
  • the pendant structure having bonded ion-exchange groups can be identified by measurement of ATR or IR absorption spectrum after the reaction for elimination of ion-exchange groups.
  • the fluorinated cation exchange membrane having sulfonic acid groups can be prepared from a membrane prepared by molding of a copolymer obtained by polymerization by converting the terminal groups of the recurring units (G) of a membrane prepared by the method as described above comprising essentially the recurring units (C) and (G) as shown below: ##STR54## (L is the same as defined above) ##STR55## (k, l, Z and R are the same as defined above) to sulfonylchloride groups --CF 2 SO 2 Cl or sulfonylbromide groups --CF 2 SO 2 Br, preferably sulfonylchloride groups, using a halogenating agent represented by the formula:
  • the reaction used in this step may be carried out according to the method and under the conditions as already described.
  • the sulfonyl halide groups formed in the above method may readily be converted to sulfonic acid groups by hydrolysis with an alkali.
  • the reaction may be accelerated by use of an organic solvent such as methanol, ethanol, dimethylsulfoxide, etc.
  • the thus prepared sulfonic acid type membrane can also be modified to have lower electric resistance by lamination with a membrane having greater exchange capacity or improved in physical strength by embedding a suitable reinforcing material, as previously described, with a membrane having both carboxylic acid groups and sulfonic acid groups.
  • reaction mixture is neutralized with 300 g of 98% sulfuric acid.
  • the sodium sulfate formed is filtered off and the filtrate is previously evaporated by an evaporator to remove tetrahydrofuran, followed by distillation of the residue, to obtain 520 g of the fraction of distillate at 84° C./30 mm Hg.
  • Said fraction is found to have the structure of C 2 H 5 SCF 2 CF 2 COOCH.sub. 3 from elemental analysis, IR and NMR spectra.
  • the compound CH 3 SCF 2 CF 2 COOH (100 g) prepared, in Example 6, by saponifying CH 3 SCF 2 CF 2 COOCH 3 , followed by acid treatment and drying treatment, is introduced into a reactor. While maintaining the temperature in the reactor at 80° to 85° C. under vigorous agitation, there are gradually added drops of a mixture (60 cc) of thionyl chloride-dimethylformamide(thionyl chloride/dimethylformamide 20/1, volume ratio). After completion of the dropwise addition, the reaction is continued until generation of hydrogen chloride gas is terminated. On termination of hydrogen chloride gas generation, the reaction mixture is distilled to give 110 g of the fraction of distillate boiling at 103°-105° C. (principally composed of CH 3 SCF 2 CF 2 COCl).
  • a reactor there are charged 140 g of NaF and 100 cc of dry tetramethylene sulfone. After heating the mixture to 85° C., under vigorous agitation, the above CH 3 SCF 2 CF 2 COCl (110 g) is added gradually dropwise into the mixture. After the reaction has continued for one hour, a vacuum line equipped with a cooling trap is connected to the reactor to reduce the pressure in the reactor to 10 mm Hg and heating is effected at 100° C. for 30 minutes. The condensed liquid product in the trap is distilled to give 80 g of the fraction of distillate at 74°-76° C.
  • Example 2 The compound C 2 H 5 SCF 2 CF 2 COOCH 3 prepared in Example 1 (330 g) is added dropwise at room temperature over one hour, while under vigorous agitation, into a reactor wherein chlorine gas (500 ml/minute) is previously passed through trifluoroacetic acid (100 ml). After said dropwise addition, the reaction mixture is left to stand for 10 hours, followed by distillation of the product and collection of the fraction of distillate at 70°-75° C./60 mm Hg to give 310 g of said fraction of distillate.
  • chlorine gas 500 ml/minute
  • trifluoroacetic acid 100 ml
  • Example 8 While passing chlorine gas at the rate of 500 ml/minute into a cold water (200 ml) previously saturated with chlorine, under vigorous agitation, the sulphenyl chloride prepared in Example 8 (226.3 g) is added gradually thereto. After the addition is completed, the reaction is continued for an additional 5 hours. Then, the lower layer is taken out to obtain 232 g of the fraction of distillate at 80°-82° C. under 60 mm Hg.
  • Example 9 The perfluoro-3-chlorosulfonylmethyl propionate (258.5 g) obtained in Example 9 is neutralized with 8N-NaOH, followed by removal of water and methanol.
  • a stainless steel autoclave of 500 cc capacity equipped with a gas blowing inlet there are charged 100 g of the compound C 2 H 5 SCF 2 CF 2 COF prepared similarly as in in Example 2, 120 g of tetraglyme(tetraethyleneglycol dimethylether) and 75 g of dry CsF. After the mixture is left to stand at room temperature for 16 hours with stirring, 80 g of hexafluoropropylene oxide (hereinafter referred to as HFPO) is blown into the autoclave while maintaining the temperature at 30° C., gradually while maintaining the pressure at 1.5 kg/cm 2 or lower.
  • HFPO hexafluoropropylene oxide
  • a 500 cc autoclave made of stainless steel equipped with a gas blowing inlet there are charged 100 g of the compound CH 3 SCF 2 CF 2 COF prepared in Example 7, 57 g of tetraglyme(tetraethyleneglycol dimethylether) and 39 g of CsF.
  • 104 g of hexafluoropropylene oxide (hereinafter referred to as HFPO) is blown into the autoclave gradually while maintaining the pressure at 1.5 kg/cm 2 or lower, while maintaining the temperature at 5° C.
  • stirring is conducted to a constant pressure and then unaltered HFPO is removed.
  • a tubular reactor made of stainless steel having a diameter of 3 cm and a length of 30 cm is filled with 100 cc of Na 2 CO 3 .
  • the filler bed While passing dry nitrogen through the reactor at the rate of 250 cc/min., the filler bed is heated externally by means of an electric heater at 350° C. to be preliminarily dried. After preliminary drying is continued for 4 hours, the rate of dry nitrogen passed is changed to 50 cc/min. and, while maintaining the filler bed at 185° to 190° C., the compound ##STR61## (120 g) as prepared in Example 11 is fed into the tubular reactor at the rate of 30 g/hr.
  • the vapor emitted from the bottom of the tube is condensed and collected in a trap cooled by dry ice-methanol.
  • the liquid composition is distilled to obtain 70 g of the fraction of distillate at 77°-80° C./100 mm Hg.
  • Example 15 is repeated except that the compound ##STR62## (120 g) prepared in Example 13 is used in place of the compound ##STR63## As the result, distillation of the reaction product gives 50 g of the fraction of distillate boiling at 82°-86° C./10 mm Hg. Said fraction is identified by elemental analysis, IR and NMR spectra to have the structure of H 5 C 2 O 2 SCF 2 CF 2 OCF ⁇ CF 2 .
  • Example 11 The compound ##STR64## as prepared in Example 11 is subjected to hydrolysis with an excess of an aqueous NaOH solution, followed by dehydration. The solid residue is washed several times with acetone to effect extraction of the sodium carboxylate. The extract is evaporated by an evaporator to remove acetone. The solid product is crushed and thoroughly dried under reduced pressure at 100° C. to obtain ##STR65## A round-bottomed glass flask of 500 cc capacity is equipped with a stirrer, a heater and an outlet for effluent gas which is connected via a trap cooled by dry ice-methanol to a vacuum line.
  • Example 15 is repeated except that the compound ##STR67## as prepared in Example 14 is used in place of ##STR68## As the result, there is obtained 65 g of the fraction of distillate boiling at 81° C./200 mm Hg.
  • Said fraction is identified by elemental analysis, IR and NMR spectra to have the structure of CH 3 SCF 2 CF 2 OCF ⁇ CF 2 .
  • Example 15 The procedure of Example 15 is repeated except that ##STR69## is used and passed through the sodium carbonate bed in place of ##STR70## whereby no objective CF 2 ⁇ CFO(CF 2 ) 2 SO 2 F is obtained but only the cyclized product ##STR71## can be obtained.
  • This copolymer is formed into a thin film for measurement of attenuated total reflection (ATR).
  • ATR attenuated total reflection
  • the above copolymer is found to have a melt index of 1.6 g/10 min., as measured under the conditions of the temperature of 250° C. and the load of 2.16 kg by means of a device with an orifice of 2.1 mm in diameter and 8 mm in length.
  • This copolymer is formed into a film with a thickness of 250 ⁇ and treated with chlorine gas at 120° C. for 20 hours, followed further by treatment with a saturated aqueous chlorine water at 83° C. for 20 hours.
  • the resultant film is subjected to measurement of ATR, whereby the absorption by ethyl groups at around 3000 cm -1 is found to be vanished and instead thereof there appears absorption due to sulfonyl chloride groups at around 1420 cm -1 .
  • the ion-exchange capacity is measured after hydrolyzing a part of said film with an alkali to be 1.3 meq/g-dry resin, indicating that the ratio of the recurring units, i.e. ##STR72##
  • This film having sulfonyl chloride groups is treated with a mixture comprising 57% hydroiodic acid and glacial acetic acid at a volume ratio of 15:1 at 72° C. for 18 hours and then hydrolyzed with an alkali. Furthermore, the thus treated membrane is treated with an aqueous 5% sodium hypochlorite solution at 90° C. for 16 hours to obtain a cation exchange membrane. Measurement of the ATR of this membrane gives the result that there are observed absorptions at 1690 cm -1 due to carboxylic acid salt form and at 1060 cm -1 due to sulfonic acid salt form.
  • the gradient of carboxylic acid density in the layer stained in blue is measured according to the following method.
  • a membrane having the same exchange capacity wherein all the ion-exchange groups are converted to carboxylic acid groups there is prepared a membrane having the same exchange capacity wherein all the ion-exchange groups are converted to carboxylic acid groups.
  • the ATR of this membrane is measured and absorbance of carboxylic acid salt at 1690 cm -1 is calculated according to the base line method, said absorbance being determined as 100.
  • the surface layer on the side having carboxylic acid salt groups of the aforesaid membrane is scraped evenly and the scraped surface is subjected to measurement of ATR, from which the absorbance of the carboxylic acid salt is calculated.
  • the percentage A% is calculated based on the absorbance of the film of the above membrane containing only carboxylic acid groups.
  • the thicknesses before and after scraping are measured to determine the difference B ⁇ therebetween.
  • the density of carboxylic acid groups in the thickness of B ⁇ from the surface layer is determined as A%.
  • the densities of carboxylic acid groups in the membrane of this Example as found in the scraped sections are 100% on the surface, 88% at the depth of 5 ⁇ from the surface, 68% at the depth of 10 ⁇ , 46% at the depth of 15 ⁇ , 26% at the depth of 20 ⁇ and 0% at the depth of 29 ⁇ .
  • the accompanying drawing shows the relation between the deepness and the density, indicating the maximum density gradient of 4.4%/ ⁇ .
  • the electrolysis performance of said membrane is measured according to the following method.
  • an electrolytic cell comprising the anode compartment and the cathode compartment separated by said membrane with a current passage area of 0.06 dm 2 (2 cm ⁇ 3 cm) and said membrane is assembled in the cell so that the surface having carboxylic acid groups may face toward the cathode side.
  • a dimensionally stable metal electrode is used and as the cathode an iron plate.
  • Into the anode compartment is charged a saturated aqueous sodium chloride solution and the pH of the anolyte is maintained at 3 by the addition of hydrochloric acid. While 10 N aqueous caustic soda solution is circulated to the cathode compartment, water is added thereto in order to maintain the concentration at a constant value.
  • the current efficiency is calculated by dividing the amount of caustic soda formed in the cathode compartment by the theoretical amount calculated from the quantity of current passed.
  • the membrane After passage of current, the membrane is observed to have no physical damage such as water bubbles, cracks or peel-off.
  • the polymer After washing the above polymer with water, the polymer is formed into a film wih a thickness of 250 ⁇ , which is in turn hydrolyzed with an alkali.
  • the resultant membrane is too low in mechanical strength to perform an evaluation thereof.
  • Comparative example 2 is repeated except that the pressure of tetrafluoroethylene is changed to 5 kg/cm 2 .
  • the resultant polymer is found to have an ion-exchange capacity of 0.89 meq/g-dry resin.
  • Said polymer is found to have a ratio of the recurring units, namely ##STR75##
  • the treated surface is hydrolyzed with an alkali, followed further by treatment with an aqueous 5% sodium hypochlorite solution at 90° C. for 16 hours.
  • an aqueous 5% sodium hypochlorite solution at 90° C. for 16 hours.
  • This membrane is provided for electrolysis evaluation according to the same method as described in Example 19, with the surface having carboxylic acid groups facing toward the cathode side.
  • the current efficiency and the voltage are measured to give the following results:
  • the membrane surface subjected to current passage is observed to find that there are water bubbles.
  • the cross-section of the membrane is also observed to find that there is peel-off in the carboxylic acid layer at the depth of 5 ⁇ from the surface layer.
  • Polymerization is conducted in the same manner as in Comparative example 2 except that the pressure of tetrafluoroethylene is changed to 5 kg/cm 2 . A part of the resultant polymer is hydrolyzed to give an ion-exchange resin having an ion-exchange capacity of 0.83 meq/g-dry resin. This polymer is molded into a film with a thickness of 50 ⁇ . This film is called film a.
  • the film a is placed on the film b and the resultant composite is subjected to press molding to give a laminated membrane.
  • This membrane after hydrolysis with an alkali, is evaluated for its electrolysis performance with the surface of the film b facing toward the cathode side. The results are shown below:
  • the membrane subjected to the passage of current After passage of current, the membrane subjected to the passage of current is found to have water bubbles formed on the entire surface. By observation of the cross-section of the membrane, there is found peel-off at exactly the interface between the film a and the film b.
  • Example 19 is repeated except that ##STR76## and CF 2 ⁇ CFO(CF 2 ) 4 COOCH 3 are used in place of CF 2 ⁇ CFOCF 2 CF 2 CF 2 SC 2 H 5 and copolymerization is carried out while blowing tetrafluoroethylene according to the method as described in Example 2 of Japanese published unexamined patent application No. 120492/1975.
  • This polymer is molded into a film with a thickness of 250 ⁇ and, after hydrolysis with an alkali, evaluated for its electrolysis performance according to the method as described in Example 19. The results are shown below.
  • One surface of the sulfonyl chloride type membrane obtained in Comparative example 3 is treated with a perfluoro-dimethylcyclobutane solution containing 5 wt.% of CF 2 ⁇ CFO(CF 2 ) 3 COOCH 3 and a catalytic amount of azobisisobutyronitrile at 50°-60° C. for 5 hours.
  • the membrane is subjected to hydrolysis treatment with 2.5 N caustic soda/50% aqueous methanol solution.
  • As the result of measurement of the ATR of the treated surface there is found specific absorption of carboxylic acid salt at 1690 cm -1 .
  • the cross-section of the membrane is stained with Malachite Green, the layer with the thickness of 4 ⁇ from the treated surface is found to be stained in blue.
  • the membrane surface subjected to current passage is found to have water bubbles formed on its entire surface.
  • the copolymers a and b are blended at a weight ratio of 50/50 on a roll mill and then press molded into a film of 100 ⁇ in thickness. This film is called film A.
  • the copolymer a is press molded into a film of 100 ⁇ in thickness. This film is called film B.
  • the films A and B are placed on each other and press molded into a laminated membrane.
  • This membrane is subjected to hydrolysis with an alkali and thereafter its electrolysis performance is measured similarly as in Example 19, with the surface of the film A facing toward the cathode side. The results are shown below.
  • Example 19 is repeated except that the reducing agents and the treatment conditions for treatment of one surface having sulfonyl chloride groups are changed as shown in Table 1.
  • the electrolysis performance, the surface density and the maximum density gradient of carboxylic acid groups are also shown in Table 1.
  • Example 19 Polymerization is carried out in the same manner as in Example 19 except that CF 2 ⁇ CFO(CF 2 ) 3 SC 2 H 5 and ##STR79## are charged at a molar ratio of 4:1. The resultant polymer is treated similarly as described in Example 19. The results obtained are similar to those as reported in Example 19.
  • Polymerization is carried out in the same manner as in Example 19 except that the pressure of tetrafluoroethylene is changed to 17 kg/cm 2 .
  • the ion-exchange capacity of a part of the resultant polymer is measured by the same method as in Example 19 to be 0.75 meq/g-dry resin.
  • the ratio of the recurring units in this polymer, i.e. ##STR80## is found to be 10.
  • the above polymer is molded into a film with a thickness of 50 ⁇ . This film is called film c.
  • the sulfide type polymer obtained in Example 19 is also molded into a film with a thickness of 100 ⁇ . This film is called a film d.
  • the film c is placed on the film d and the composite is press molded into a laminated membrane. Then, with the side of the film d downward, said membrane is placed on a fabric made of polytetrafluoroethylene, which is "leno-woven" fabric with a thickness of about 0.15 mm comprising wefts of 400 denier multi-filaments and warps of 200 denier multi-filaments ⁇ 2. By heating the membrane under vacuo, the fabric is embedded in the film d to reinforce said membrane.
  • the laminated membrane incorporated with a reinforcing material is subjected to the chlorine treatment similarly as in Example 19 to form a sulfonyl chloride type laminated membrane.
  • Said laminated membrane is treated on the side of the film c with a mixture comprising 57% hydroiodic acid and glacial acetic acid at a volume ratio of 10:1 at 83° C. for 20 hours. After hydrolysis with an alkali, the membrane is further treated with 5% sodium hypochlorite at 90° C. for 16 hours.
  • the cross-section of the resultant membrane is stained with an aqueous Malachite Green solution adjusted at pH 2, the layer with thickness of 11 ⁇ from the surface of the film c is stained in blue, the residual part being stained in yellow.
  • the maximum density gradient of carboxylic acid groups in the layer stained blue is measured to be 4.9%/ ⁇ , and the density of carboxylic acid groups on the surface to be 92%.
  • Example 23 The laminated membrane prepared in Example 23 is treated on the side of the film c with the reducing agents and under the treatment conditions as shown in Table 2, followed by subsequent treatments similarly conducted as in Example 23.
  • the electrolysis performance, the density of carboxylic acid groups on the surface of the film c and the maximum density gradient are set forth in Table 2.
  • a part of this polymer is hydrolyzed with an alkali containing potassium permanganate and the ion-exchange capacity of the hydrolyzed polymer is measured to be 1.31 meq/g-dry resin.
  • the above sulfonic type polymer is molded into a membrane with a thickness of 250 ⁇ , which is then hydrolyzed with an alkali containing potassium permanganate. Subsequently, said membrane is immersed in a mixture comprising 1:3 (weight ratio) of phosphorus pentachloride and phosphorus oxychloride to be treated at 110° C. for 20 hours. Measurement of the ATR of the resultant membrane gives the result that there appears specific absorption of sulfonyl chloride groups at 1420 cm -1 .
  • sulfonyl chloride type membrane After one surface of said sulfonyl chloride type membrane is treated with a mixture comprising 15:1 (volume ratio) of hydroiodic acid and propionic acid at 72° C. for 18 hours, the treated membrane is subjected to hydrolysis treatment with an alkali, followed further by treatment with an aqueous 5% sodium hypochlorite solution at 90° C. for 16 hours.
  • hydrolysis treatment with an alkali
  • an aqueous 5% sodium hypochlorite solution at 90° C. for 16 hours.
  • the cross-section of the membrane is stained with an aqueous Malachite Green solution, the layer with a thickness of 11 ⁇ from one surface is found to be stained in blue, while the remaining portion is stained in yellow.
  • the surface density and the maximum density gradient of carboxylic acid groups in the layer stained in blue are found to be 100% and 5.1%/ ⁇ , respectively.
  • Example 28 One surface of the sulfonyl chloride type membrane prepared in Example 28 is treated similarly as in Example 28 using various reducing agents and treatment conditions as shown in Table 3. The density of carboxylic acid groups on the surface of the membrane and the maximum density gradient of carboxylic acid groups are also shown for each membrane obtained in Table 3.
  • the copolymer prepared according to the polymerization method as described in Example 19 is extruded into a strand, which is then cut into a granular resin of 1 mm in size by means of a pelletizer.
  • the functional groups contained in said resin are converted to sulfonyl chloride groups by the method as described in Example 19, followed by hydrolysis to be converted to sulfonic acid groups. Then, the ion-exchange capacity of the resin is measured to be 1.3 meq/g-dry resin.
  • An emulsion is formed in a stainless steel autoclave of 300 cc capacity by charging 10 g of CF 2 ⁇ CFO(CF 2 ) 3 SCH 3 , 1.0 g of sodium hydrogen phosphate, 45 cc of purified water and 0.45 g of ammonium perfluorooctanoate. Then, 5 cc of 0.62% aqueous ammonium persulfate solution is carried to the emulsion and polymerization is carried out, while maintaining the temperature at 40° C., under the pressure of tetrafluoroethylene of 13 kg/cm 2 , whereby the pressure of tetrafluoroethylene is controlled so as to keep constant the polymerization rate.
  • the resultant polymer is found to contain 3.50 wt.% of sulfur by elemental analysis.
  • This polymer is press molded into a thin film at 280° C. and subjected to measurement of ATR, whereby there is observed absorption of methyl groups at 3000 cm -1 .
  • the above polymer is molded into a membrane with a thickness of 150 ⁇ , which is in turn treated with chlorine gas at 120° C. for 20 hours. Measurement of the ATR of the membrane gives the result that the absorption of methyl groups at around 3000 cm -1 has vanished. Furthermore, said membrane is treated with a liquid saturated with chlorine, comprising a mixture of perfluorobutyric acid and water (2:1, volume ratio) having dissolved chlorine therein, at 100° C. for 48 hours. Measurement of the ATR of said membrane shows that there appears absorption of sulfonyl chloride groups at around 1420 cm -1 . Ion-exchange capacity of said membrane is determined after hydrolysis of a part thereof with an alkali to be 1.04 meq/g-dry resin. The ratio of the recurring units of the membrane, i.e. ##STR81## is found to be 6.7.
  • One surface of the above sulfonyl chloride type membrane is treated with a mixture comprising 57% hydroiodic acid and acetic acid at 30:1 (volume ratio) at 72° C. for 16 hours, followed by hydrolysis with an alkali, and further treated with an aqueous 5% sodium hypochlorite solution at 90° C. for 16 hours.
  • aqueous 5% sodium hypochlorite solution at 90° C. for 16 hours.
  • An emulsion is formed in a stainless steel autoclave of 300 cc capacity by charging 10 g of CF 2 ⁇ CFO(CF 2 ) 3 SC 2 H 5 , 0.1 g of ammonium persulfate and water, using ammonium perfluorooctanoate as emulsifier.
  • Tetrafluoroethylene is pressurized into the autoclave at 15 kg/cm 2 and polymerization is carried out at 50° C. by adding sodium hydrogen sulfite as co-catalyst.
  • the resultant polymer is found to contain 4.23 wt.% of sulfur by elemental analysis.
  • This polymer is molded into a membrane with a thickness of 250 ⁇ , which is in turn treated with chlorine gas at 120° C.
  • the electrolysis performance of said membrane is measured according to the following method.
  • an electrolytic cell comprising the anode compartment and the cathode compartment separated by said membrane with a current passage area of 0.06 dm 2 (2 cm ⁇ 3 cm) and said membrane is assembled in the cell.
  • a dimensionally stable electrode is used and as the cathode an iron plate.
  • a saturated aqueous sodium chloride solution is charged into the anode compartment and adjusted at pH 3 by adding hydrochloric acid thereto. While 13 N aqueous caustic soda solution is circulated to the cathode compartment, water is added thereto in order to maintain the concentration at a constant value.
  • An emulsion is formed by charging 10 g of CF 2 ⁇ CFO(CF 2 ) 3 SCH 3 , 1.0 g of sodium hydrogen phosphate, 45 cc of purified water and 0.45 g of ammonium perfluorooctanoate in a stainless steel autoclave of 300 cc capacity. Then, 5 cc of an aqueous 0.62% ammonium persulfate solution is added to the mixture, and polymerization is conducted under the pressure of tetrafluoroethylene of 13 kg/cm 2 , while maintaining the temperature at 40° C. During the polymerization, the pressure of tetrafluoroethylene is controlled so as to keep constant the rate of polymerization.
  • the resultant polymer is found to contain 3.5 wt.% of sulfur by elemental analysis.
  • This polymer is press molded at 280° C. into a thin film, which is subjected to measurement of ATR, whereby it is found that there is observed absorption of methyl groups at around 3000 cm -1 .
  • a membrane with a thickness of 150 ⁇ prepared by molding of the above polymer is treated with chlorine gas at 120° C. for 20 hours, whereby absorption of methyl groups at around 3000 cm -1 is found to have vanished as measured by the ATR of the membrane. Further, said membrane is treated with a liquid saturated with chlorine, comprising a mixture of perfluorobutyric acid and water at 2:1 (volume ratio) having dissolved chlorine therein, at 100° C. for 48 hours. Measurement of the ATR of the resultant membrane gives the result that there appears absorption of sulfonyl groups at around 1420 cm -1 .
  • the ion-exchange capacity of said membrane is measured after hydrolysis of said membrane with an alkali to be 1.04 meq/g-dry resin, thus giving the ratio of the recurring units of the membrane, i.e. ##STR83## of 6.7.
  • the polymer prepared in Example 19 is molded into a film with a thickness of 200 ⁇ .
  • a fabric made of polytetrafluoroethylene fibers is embedded in this film according to the following method.
  • the device used in this embedding procedure comprises two aluminum plates, each being provided on the upper surface by mechanical working with a series of grooves so as to create a pressure difference across the upper surface of the plate. The pressure difference is applied through the hole bored through the side surface of the plate, said hole being connected to the grooves on the upper surface of the plate. On this plate is placed a 60-mesh wire-screen so that the pressure difference may be applied on every point on the upper surface.
  • a sheet of asbestos paper is placed on the upper surface of the wire-screen, and on said sheet is superposed a "leon-woven" fabric with a thickness of about 0.15 mm made of polytetrafluoroethylene fibers comprising, each 25 per inch, 400 denier multi-filaments as weft and 200 denier multifilaments ⁇ 2 as warp.
  • a "leon-woven" fabric with a thickness of about 0.15 mm made of polytetrafluoroethylene fibers comprising, each 25 per inch, 400 denier multi-filaments as weft and 200 denier multifilaments ⁇ 2 as warp.
  • On said fabric is further placed the above film.
  • the size of the film is made slightly larger than the other components and the marginals of the sheets of the fluorinated polymer are fastened onto the aluminum plates with a tape, thus forming an air-tight package.
  • the embedding device is placed between the elctrically heated hot plates, whereby the hot plate contacted with the aluminum plate is maintained at 300° C. and the hot plate contacted with the film at 180° C. for 5 minutes. Then, through the hole on the side surface of the aluminum plate, evacuation is effected to provide a 100 mm Hg pressure difference. Under such conditions, the whole composite is left to stand for 3 minutes. The temperature of the hot plates is then cooled to room temperature and the pressure difference is removed. By observation of the cross-section of the film, the fabric is completely embedded within the film.

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US06/152,847 1979-05-31 1980-05-23 Novel fluorinated cation exchange membrane and process for producing the same Expired - Lifetime US4329434A (en)

Applications Claiming Priority (10)

Application Number Priority Date Filing Date Title
JP54/67888 1979-05-31
JP54/67889 1979-05-31
JP6788979A JPS55160007A (en) 1979-05-31 1979-05-31 Novel fluorinated copolymer and production thereof
JP54067888A JPS6045653B2 (ja) 1979-05-31 1979-05-31 新規なフツ素化陽イオン交換膜及びその製造方法
JP54/85852 1979-07-09
JP54085852A JPS5910658B2 (ja) 1979-07-09 1979-07-09 新規なフツ素化ビニルエ−テル化合物及びその製法
JP9030279A JPS5616460A (en) 1979-07-18 1979-07-18 Novel fluorinated carboxylic acid derivative and its preparation
JP54/90301 1979-07-18
JP9030179A JPS5912116B2 (ja) 1979-07-18 1979-07-18 新規なフッ素化酸フッ化物及びその製造方法
JP54/90302 1979-07-18

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US06/527,425 Expired - Lifetime US4555369A (en) 1979-05-31 1983-08-29 Fluorinated ether acyl fluorides having alkylthio or alkylsulfone groups
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US06/527,426 Expired - Lifetime US4597913A (en) 1979-05-31 1983-08-29 Intermediates for fluorinated cation exchange membrane

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US4526948A (en) * 1983-12-27 1985-07-02 E. I. Du Pont De Nemours And Company Fluorinated vinyl ethers, copolymers thereof, and precursors thereto
US4556747A (en) * 1983-12-27 1985-12-03 E. I. Du Pont De Nemours And Company Fluorinated vinyl ethers, copolymers thereof, and precursors thereto
US4590015A (en) * 1983-12-27 1986-05-20 E. I. Du Pont De Nemours And Company Fluorinated polyether carboxylic acid fluorides
US4604323A (en) * 1985-02-22 1986-08-05 E. I. Du Pont De Nemours And Company Multilayer cation exchange membrane
US4626553A (en) * 1980-11-29 1986-12-02 Asahi Kasei Kogyo Kabushiki Kaisha Cation exchange membrane of a fluorocarbon polymer and a process for preparing the same
US4675453A (en) * 1983-12-27 1987-06-23 E. I. Du Pont De Nemours And Company Process and intermediates for fluorinated vinyl ether monomer
US4680355A (en) * 1984-03-12 1987-07-14 Tokuyama Soda Kabushiki Kaisha Process for preparation of fluorine containing polymer films
WO1989002457A1 (en) * 1987-09-17 1989-03-23 Telectronics Pty. Limited Neutralized perfluoro-3,6-dioxa-4-methyl-7-octene sulphonyl fluoride copolymer surface for attachment and growth of animal cells
US4844719A (en) * 1985-02-09 1989-07-04 Asahi Kasei Kogyo Kabushiki Kaisha Permeable polymer membrane for dessication of gas
US4940525A (en) * 1987-05-08 1990-07-10 The Dow Chemical Company Low equivalent weight sulfonic fluoropolymers
US4940814A (en) * 1987-03-07 1990-07-10 Hoechst Aktiengesellschaft Reaction of hexafluoropropene oxide with fluorinated carboxylic acid fluorides
US5006624A (en) * 1987-05-14 1991-04-09 The Dow Chemical Company Fluorocarbon containing, reactive polymeric surfactants and coating compositions therefrom
US5536754A (en) * 1995-02-15 1996-07-16 E. I. Du Pont De Nemours And Company Fluorinated ion-exchange polymers and intermediates therefor
WO1998002207A1 (en) * 1996-07-12 1998-01-22 Empi, Inc. Iontophoresis electrode
US5830962A (en) * 1995-02-15 1998-11-03 E. I. Du Pont De Nemours And Company Fluorinated ion-exchange polymers and intermediates therefor
US5871461A (en) * 1996-07-12 1999-02-16 Empi, Inc. Method of making an iontophoresis electrode
US6107422A (en) * 1995-01-24 2000-08-22 E.I. Du Pont De Nemours And Company Copolymer of an olefin and an unsaturated partially fluorinated functionalized monomer
US6624328B1 (en) 2002-12-17 2003-09-23 3M Innovative Properties Company Preparation of perfluorinated vinyl ethers having a sulfonyl fluoride end-group
WO2003104293A1 (es) * 2002-06-07 2003-12-18 David Fuel Cell Components, S.L. Método de obtención de polímeros perfluorosulfonados que contienen grupos funcionales sulfonilo
US20040121210A1 (en) * 2002-12-19 2004-06-24 3M Innovative Properties Company Polymer electrolyte membrane
WO2015015513A2 (en) 2013-07-31 2015-02-05 Council Of Scientific & Industrial Research Anion exchange membrane for electrodialysis applications and process for the preparation thereof
US10695744B2 (en) 2015-06-05 2020-06-30 W. R. Grace & Co.-Conn. Adsorbent biprocessing clarification agents and methods of making and using the same
US11389783B2 (en) 2014-05-02 2022-07-19 W.R. Grace & Co.-Conn. Functionalized support material and methods of making and using functionalized support material
US11628381B2 (en) 2012-09-17 2023-04-18 W.R. Grace & Co. Conn. Chromatography media and devices

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US4786442A (en) * 1980-04-03 1988-11-22 E. I. Du Pont De Nemours And Company Alkyl perfluoro(2-methyl-5-oxo-3-oxahexanoate)
JPS58199884A (ja) * 1982-05-18 1983-11-21 Asahi Glass Co Ltd 改良された電解用陽イオン交換膜
US4766248A (en) * 1982-07-19 1988-08-23 E. I. Du Pont De Nemours And Company β-substituted polyfluoroethyl compounds
DE3768388D1 (de) * 1986-09-19 1991-04-11 Ausimont Spa Verfahren zur herstellung von perfluoracylfluoriden.
US5475143A (en) * 1995-02-15 1995-12-12 E. I. Du Pont De Nemours And Company Fluorinated ion-exchange polymers and intermediates therefor
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US5782472A (en) * 1995-09-25 1998-07-21 Steven R. Pyykkonen Device for combining a game of chance and craps
US6285816B1 (en) * 1999-04-13 2001-09-04 Wisconsin Alumni Research Foundation Waveguide
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ITMI20030444A1 (it) * 2003-03-11 2004-09-12 Solvay Solexis Spa Processo per preparare (per)fluoroalogenoeteri.
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US10756373B2 (en) * 2017-12-22 2020-08-25 Chinbay Q. Fan Fuel cell system and method of providing surfactant fuel bubbles
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Cited By (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4626553A (en) * 1980-11-29 1986-12-02 Asahi Kasei Kogyo Kabushiki Kaisha Cation exchange membrane of a fluorocarbon polymer and a process for preparing the same
US4399009A (en) * 1981-01-19 1983-08-16 Oronzio Denora Impianti Elettrochimici S.P.A. Electrolytic cell and method
US4526948A (en) * 1983-12-27 1985-07-02 E. I. Du Pont De Nemours And Company Fluorinated vinyl ethers, copolymers thereof, and precursors thereto
US4556747A (en) * 1983-12-27 1985-12-03 E. I. Du Pont De Nemours And Company Fluorinated vinyl ethers, copolymers thereof, and precursors thereto
US4590015A (en) * 1983-12-27 1986-05-20 E. I. Du Pont De Nemours And Company Fluorinated polyether carboxylic acid fluorides
US4474899A (en) * 1983-12-27 1984-10-02 E. I. Du Pont De Nemours And Company Process for preparing ester fluorinated ion exchange polymer precursor by acid treatment of ether
US4675453A (en) * 1983-12-27 1987-06-23 E. I. Du Pont De Nemours And Company Process and intermediates for fluorinated vinyl ether monomer
US4680355A (en) * 1984-03-12 1987-07-14 Tokuyama Soda Kabushiki Kaisha Process for preparation of fluorine containing polymer films
US4844719A (en) * 1985-02-09 1989-07-04 Asahi Kasei Kogyo Kabushiki Kaisha Permeable polymer membrane for dessication of gas
US4604323A (en) * 1985-02-22 1986-08-05 E. I. Du Pont De Nemours And Company Multilayer cation exchange membrane
US4940814A (en) * 1987-03-07 1990-07-10 Hoechst Aktiengesellschaft Reaction of hexafluoropropene oxide with fluorinated carboxylic acid fluorides
US4940525A (en) * 1987-05-08 1990-07-10 The Dow Chemical Company Low equivalent weight sulfonic fluoropolymers
US5006624A (en) * 1987-05-14 1991-04-09 The Dow Chemical Company Fluorocarbon containing, reactive polymeric surfactants and coating compositions therefrom
US5077215A (en) * 1987-09-17 1991-12-31 Telectronics Pty. Limited Neutralized perfluoro-3,6-dioxa-4-methyl-7-octene sulphonyl fluoride copolymer surface for attachment and growth of animal cells
WO1989002457A1 (en) * 1987-09-17 1989-03-23 Telectronics Pty. Limited Neutralized perfluoro-3,6-dioxa-4-methyl-7-octene sulphonyl fluoride copolymer surface for attachment and growth of animal cells
US6107422A (en) * 1995-01-24 2000-08-22 E.I. Du Pont De Nemours And Company Copolymer of an olefin and an unsaturated partially fluorinated functionalized monomer
US5536754A (en) * 1995-02-15 1996-07-16 E. I. Du Pont De Nemours And Company Fluorinated ion-exchange polymers and intermediates therefor
US5668233A (en) * 1995-02-15 1997-09-16 E. I. Du Pont De Nemours And Company Fluorinated ion-exchange polymers and intermediates therefor
US5830962A (en) * 1995-02-15 1998-11-03 E. I. Du Pont De Nemours And Company Fluorinated ion-exchange polymers and intermediates therefor
WO1998002207A1 (en) * 1996-07-12 1998-01-22 Empi, Inc. Iontophoresis electrode
US5871461A (en) * 1996-07-12 1999-02-16 Empi, Inc. Method of making an iontophoresis electrode
WO2003104293A1 (es) * 2002-06-07 2003-12-18 David Fuel Cell Components, S.L. Método de obtención de polímeros perfluorosulfonados que contienen grupos funcionales sulfonilo
US6624328B1 (en) 2002-12-17 2003-09-23 3M Innovative Properties Company Preparation of perfluorinated vinyl ethers having a sulfonyl fluoride end-group
US20040121210A1 (en) * 2002-12-19 2004-06-24 3M Innovative Properties Company Polymer electrolyte membrane
US7348088B2 (en) 2002-12-19 2008-03-25 3M Innovative Properties Company Polymer electrolyte membrane
US11628381B2 (en) 2012-09-17 2023-04-18 W.R. Grace & Co. Conn. Chromatography media and devices
WO2015015513A2 (en) 2013-07-31 2015-02-05 Council Of Scientific & Industrial Research Anion exchange membrane for electrodialysis applications and process for the preparation thereof
US11389783B2 (en) 2014-05-02 2022-07-19 W.R. Grace & Co.-Conn. Functionalized support material and methods of making and using functionalized support material
US10695744B2 (en) 2015-06-05 2020-06-30 W. R. Grace & Co.-Conn. Adsorbent biprocessing clarification agents and methods of making and using the same

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SE8003901L (sv) 1980-12-01
DE3046501C2 (de) 1987-04-23
FR2508039B1 (nl) 1985-02-15
FR2457880B1 (nl) 1986-07-04
FR2473533A1 (fr) 1981-07-17
DE3050782C2 (nl) 1988-05-26
IN154418B (nl) 1984-10-27
DE3020057A1 (de) 1981-05-27
FR2473533B1 (fr) 1986-02-28
CA1185398A (en) 1985-04-09
NL184740C (nl) 1989-10-16
FI72530B (fi) 1987-02-27
DE3050439A1 (nl) 1982-07-22
IT1193942B (it) 1988-08-31
BR8003432A (pt) 1981-01-05
SE449999B (sv) 1987-06-01
FR2483431B1 (fr) 1986-03-21
NO153398B (no) 1985-12-02
US4555369A (en) 1985-11-26
NO153398C (no) 1986-03-12
FR2457880A1 (nl) 1980-12-26
DE3050439C2 (nl) 1989-11-09
US4597913A (en) 1986-07-01
NL8003174A (nl) 1980-12-02
IT8022468A0 (it) 1980-05-30
FR2508039A1 (nl) 1982-12-24
FI801733A (fi) 1980-12-01
FR2483431A1 (fr) 1981-12-04
PT72131B (en) 1981-09-24
NO801637L (no) 1980-12-01
US4510328A (en) 1985-04-09
PT72131A (en) 1980-12-01
DE3020057C2 (nl) 1987-06-25
CA1168263A (en) 1984-05-29
FI72530C (fi) 1987-06-08
DE3046501A1 (de) 1983-02-17

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